Iα to Iβ mechano-conversion and amorphization in native cellulose simulated by crystal bending
Iα to Iβ mechano-conversion and amorphization in native cellulose simulated by crystal bending
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通过晶体弯曲模拟天然纤维素中 Iα 到 Iβ 的机械转换和非晶化
DOI：
10.1007/s10570-018-1860-x
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发表时间：
2018
期刊：
影响因子：
5.7
通讯作者：
K. Mazeau
中科院分区：
文献类型：
--
作者：
Pan Chen;Y. Ogawa;Y. Nishiyama;A. Ismail;K. Mazeau
用分子动力学方法模拟聚合度分别为40和160时的天然纤维素棒状晶体的弯曲行为，结果表明，弯曲段中的纤维素I-α和I-β发生了变形诱导的局部非晶化和异形互变。转化机理是氢键的链条纵向滑移1个无氢葡萄糖残基的长度(~ 0.5 nm)，从而使链的堆积从单调的(Iα)形式改变为交替的Iβ形式，反之亦然。这种机械变形使I-α形式逐渐转变为I-β形式，正如已在实验中观察到的微纤维的超声作用。Iβ也能够部分转换为类似Iα的组织，但这种转换只是暂时的。超声作用下微纤维的行为与电子显微镜观察到的Iα → Iβ转化率之间的定性一致表明，弯曲变形下的剪切变形和链滑移是纤维素纤维承受侧向机械应力时的一般过程。
The bending of rod-like native cellulose crystals with degree of polymerization 40 and 160 using molecular dynamics simulations resulted in a deformation-induced local amorphization at the kinking point and allomorphic interconversion between cellulose Iα and Iβ in the unbent segments. The transformation mechanism involves a longitudinal chain slippage of the hydrogen-bonded sheets by the length of one anhydroglucose residue (~ 0.5 nm), which alters the chain stacking from the monotonic (Iα) form to the alternating Iβ one or vice versa. This mechanical deformation converts the Iα form progressively to the Iβ form, as has been experimentally observed for ultrasonication of microfibrils. Iβ is also able to partially convert to Iα-like organization but this conversion is only transitory. The qualitative agreement between the behavior of ultrasonicated microfibrils and in silico observed Iα → Iβ conversion suggests that shear deformation and chain slippage under bending deformation is a general process when cellulose fibrils experience lateral mechanical stress.
影响因子：
15
作者：
Nishiyama, Y;Langan, P;Chanzy, H
通讯作者：
Chanzy, H